/*
 * Copyright (c) 2012-2020 MIRACL UK Ltd.
 *
 * This file is part of MIRACL Core
 * (see https://github.com/miracl/core).
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* AES Encryption */

package core

//import "fmt"

const AES_ECB int = 0
const AES_CBC int = 1
const AES_CFB1 int = 2
const AES_CFB2 int = 3
const AES_CFB4 int = 5
const AES_OFB1 int = 14
const AES_OFB2 int = 15
const AES_OFB4 int = 17
const AES_OFB8 int = 21
const AES_OFB16 int = 29
const AES_CTR1 int = 30
const AES_CTR2 int = 31
const AES_CTR4 int = 33
const AES_CTR8 int = 37
const AES_CTR16 int = 45

var aes_InCo = [...]byte{0xB, 0xD, 0x9, 0xE} /* Inverse Coefficients */

var aes_ptab = [...]byte{
	1, 3, 5, 15, 17, 51, 85, 255, 26, 46, 114, 150, 161, 248, 19, 53,
	95, 225, 56, 72, 216, 115, 149, 164, 247, 2, 6, 10, 30, 34, 102, 170,
	229, 52, 92, 228, 55, 89, 235, 38, 106, 190, 217, 112, 144, 171, 230, 49,
	83, 245, 4, 12, 20, 60, 68, 204, 79, 209, 104, 184, 211, 110, 178, 205,
	76, 212, 103, 169, 224, 59, 77, 215, 98, 166, 241, 8, 24, 40, 120, 136,
	131, 158, 185, 208, 107, 189, 220, 127, 129, 152, 179, 206, 73, 219, 118, 154,
	181, 196, 87, 249, 16, 48, 80, 240, 11, 29, 39, 105, 187, 214, 97, 163,
	254, 25, 43, 125, 135, 146, 173, 236, 47, 113, 147, 174, 233, 32, 96, 160,
	251, 22, 58, 78, 210, 109, 183, 194, 93, 231, 50, 86, 250, 21, 63, 65,
	195, 94, 226, 61, 71, 201, 64, 192, 91, 237, 44, 116, 156, 191, 218, 117,
	159, 186, 213, 100, 172, 239, 42, 126, 130, 157, 188, 223, 122, 142, 137, 128,
	155, 182, 193, 88, 232, 35, 101, 175, 234, 37, 111, 177, 200, 67, 197, 84,
	252, 31, 33, 99, 165, 244, 7, 9, 27, 45, 119, 153, 176, 203, 70, 202,
	69, 207, 74, 222, 121, 139, 134, 145, 168, 227, 62, 66, 198, 81, 243, 14,
	18, 54, 90, 238, 41, 123, 141, 140, 143, 138, 133, 148, 167, 242, 13, 23,
	57, 75, 221, 124, 132, 151, 162, 253, 28, 36, 108, 180, 199, 82, 246, 1}

var aes_ltab = [...]byte{
	0, 255, 25, 1, 50, 2, 26, 198, 75, 199, 27, 104, 51, 238, 223, 3,
	100, 4, 224, 14, 52, 141, 129, 239, 76, 113, 8, 200, 248, 105, 28, 193,
	125, 194, 29, 181, 249, 185, 39, 106, 77, 228, 166, 114, 154, 201, 9, 120,
	101, 47, 138, 5, 33, 15, 225, 36, 18, 240, 130, 69, 53, 147, 218, 142,
	150, 143, 219, 189, 54, 208, 206, 148, 19, 92, 210, 241, 64, 70, 131, 56,
	102, 221, 253, 48, 191, 6, 139, 98, 179, 37, 226, 152, 34, 136, 145, 16,
	126, 110, 72, 195, 163, 182, 30, 66, 58, 107, 40, 84, 250, 133, 61, 186,
	43, 121, 10, 21, 155, 159, 94, 202, 78, 212, 172, 229, 243, 115, 167, 87,
	175, 88, 168, 80, 244, 234, 214, 116, 79, 174, 233, 213, 231, 230, 173, 232,
	44, 215, 117, 122, 235, 22, 11, 245, 89, 203, 95, 176, 156, 169, 81, 160,
	127, 12, 246, 111, 23, 196, 73, 236, 216, 67, 31, 45, 164, 118, 123, 183,
	204, 187, 62, 90, 251, 96, 177, 134, 59, 82, 161, 108, 170, 85, 41, 157,
	151, 178, 135, 144, 97, 190, 220, 252, 188, 149, 207, 205, 55, 63, 91, 209,
	83, 57, 132, 60, 65, 162, 109, 71, 20, 42, 158, 93, 86, 242, 211, 171,
	68, 17, 146, 217, 35, 32, 46, 137, 180, 124, 184, 38, 119, 153, 227, 165,
	103, 74, 237, 222, 197, 49, 254, 24, 13, 99, 140, 128, 192, 247, 112, 7}

var aes_fbsub = [...]byte{
	99, 124, 119, 123, 242, 107, 111, 197, 48, 1, 103, 43, 254, 215, 171, 118,
	202, 130, 201, 125, 250, 89, 71, 240, 173, 212, 162, 175, 156, 164, 114, 192,
	183, 253, 147, 38, 54, 63, 247, 204, 52, 165, 229, 241, 113, 216, 49, 21,
	4, 199, 35, 195, 24, 150, 5, 154, 7, 18, 128, 226, 235, 39, 178, 117,
	9, 131, 44, 26, 27, 110, 90, 160, 82, 59, 214, 179, 41, 227, 47, 132,
	83, 209, 0, 237, 32, 252, 177, 91, 106, 203, 190, 57, 74, 76, 88, 207,
	208, 239, 170, 251, 67, 77, 51, 133, 69, 249, 2, 127, 80, 60, 159, 168,
	81, 163, 64, 143, 146, 157, 56, 245, 188, 182, 218, 33, 16, 255, 243, 210,
	205, 12, 19, 236, 95, 151, 68, 23, 196, 167, 126, 61, 100, 93, 25, 115,
	96, 129, 79, 220, 34, 42, 144, 136, 70, 238, 184, 20, 222, 94, 11, 219,
	224, 50, 58, 10, 73, 6, 36, 92, 194, 211, 172, 98, 145, 149, 228, 121,
	231, 200, 55, 109, 141, 213, 78, 169, 108, 86, 244, 234, 101, 122, 174, 8,
	186, 120, 37, 46, 28, 166, 180, 198, 232, 221, 116, 31, 75, 189, 139, 138,
	112, 62, 181, 102, 72, 3, 246, 14, 97, 53, 87, 185, 134, 193, 29, 158,
	225, 248, 152, 17, 105, 217, 142, 148, 155, 30, 135, 233, 206, 85, 40, 223,
	140, 161, 137, 13, 191, 230, 66, 104, 65, 153, 45, 15, 176, 84, 187, 22}

var aes_rbsub = [...]byte{
	82, 9, 106, 213, 48, 54, 165, 56, 191, 64, 163, 158, 129, 243, 215, 251,
	124, 227, 57, 130, 155, 47, 255, 135, 52, 142, 67, 68, 196, 222, 233, 203,
	84, 123, 148, 50, 166, 194, 35, 61, 238, 76, 149, 11, 66, 250, 195, 78,
	8, 46, 161, 102, 40, 217, 36, 178, 118, 91, 162, 73, 109, 139, 209, 37,
	114, 248, 246, 100, 134, 104, 152, 22, 212, 164, 92, 204, 93, 101, 182, 146,
	108, 112, 72, 80, 253, 237, 185, 218, 94, 21, 70, 87, 167, 141, 157, 132,
	144, 216, 171, 0, 140, 188, 211, 10, 247, 228, 88, 5, 184, 179, 69, 6,
	208, 44, 30, 143, 202, 63, 15, 2, 193, 175, 189, 3, 1, 19, 138, 107,
	58, 145, 17, 65, 79, 103, 220, 234, 151, 242, 207, 206, 240, 180, 230, 115,
	150, 172, 116, 34, 231, 173, 53, 133, 226, 249, 55, 232, 28, 117, 223, 110,
	71, 241, 26, 113, 29, 41, 197, 137, 111, 183, 98, 14, 170, 24, 190, 27,
	252, 86, 62, 75, 198, 210, 121, 32, 154, 219, 192, 254, 120, 205, 90, 244,
	31, 221, 168, 51, 136, 7, 199, 49, 177, 18, 16, 89, 39, 128, 236, 95,
	96, 81, 127, 169, 25, 181, 74, 13, 45, 229, 122, 159, 147, 201, 156, 239,
	160, 224, 59, 77, 174, 42, 245, 176, 200, 235, 187, 60, 131, 83, 153, 97,
	23, 43, 4, 126, 186, 119, 214, 38, 225, 105, 20, 99, 85, 33, 12, 125}

var aes_rco = [...]byte{1, 2, 4, 8, 16, 32, 64, 128, 27, 54, 108, 216, 171, 77, 154, 47}

var aes_ftable = [...]uint32{
	0xa56363c6, 0x847c7cf8, 0x997777ee, 0x8d7b7bf6, 0xdf2f2ff, 0xbd6b6bd6,
	0xb16f6fde, 0x54c5c591, 0x50303060, 0x3010102, 0xa96767ce, 0x7d2b2b56,
	0x19fefee7, 0x62d7d7b5, 0xe6abab4d, 0x9a7676ec, 0x45caca8f, 0x9d82821f,
	0x40c9c989, 0x877d7dfa, 0x15fafaef, 0xeb5959b2, 0xc947478e, 0xbf0f0fb,
	0xecadad41, 0x67d4d4b3, 0xfda2a25f, 0xeaafaf45, 0xbf9c9c23, 0xf7a4a453,
	0x967272e4, 0x5bc0c09b, 0xc2b7b775, 0x1cfdfde1, 0xae93933d, 0x6a26264c,
	0x5a36366c, 0x413f3f7e, 0x2f7f7f5, 0x4fcccc83, 0x5c343468, 0xf4a5a551,
	0x34e5e5d1, 0x8f1f1f9, 0x937171e2, 0x73d8d8ab, 0x53313162, 0x3f15152a,
	0xc040408, 0x52c7c795, 0x65232346, 0x5ec3c39d, 0x28181830, 0xa1969637,
	0xf05050a, 0xb59a9a2f, 0x907070e, 0x36121224, 0x9b80801b, 0x3de2e2df,
	0x26ebebcd, 0x6927274e, 0xcdb2b27f, 0x9f7575ea, 0x1b090912, 0x9e83831d,
	0x742c2c58, 0x2e1a1a34, 0x2d1b1b36, 0xb26e6edc, 0xee5a5ab4, 0xfba0a05b,
	0xf65252a4, 0x4d3b3b76, 0x61d6d6b7, 0xceb3b37d, 0x7b292952, 0x3ee3e3dd,
	0x712f2f5e, 0x97848413, 0xf55353a6, 0x68d1d1b9, 0x0, 0x2cededc1,
	0x60202040, 0x1ffcfce3, 0xc8b1b179, 0xed5b5bb6, 0xbe6a6ad4, 0x46cbcb8d,
	0xd9bebe67, 0x4b393972, 0xde4a4a94, 0xd44c4c98, 0xe85858b0, 0x4acfcf85,
	0x6bd0d0bb, 0x2aefefc5, 0xe5aaaa4f, 0x16fbfbed, 0xc5434386, 0xd74d4d9a,
	0x55333366, 0x94858511, 0xcf45458a, 0x10f9f9e9, 0x6020204, 0x817f7ffe,
	0xf05050a0, 0x443c3c78, 0xba9f9f25, 0xe3a8a84b, 0xf35151a2, 0xfea3a35d,
	0xc0404080, 0x8a8f8f05, 0xad92923f, 0xbc9d9d21, 0x48383870, 0x4f5f5f1,
	0xdfbcbc63, 0xc1b6b677, 0x75dadaaf, 0x63212142, 0x30101020, 0x1affffe5,
	0xef3f3fd, 0x6dd2d2bf, 0x4ccdcd81, 0x140c0c18, 0x35131326, 0x2fececc3,
	0xe15f5fbe, 0xa2979735, 0xcc444488, 0x3917172e, 0x57c4c493, 0xf2a7a755,
	0x827e7efc, 0x473d3d7a, 0xac6464c8, 0xe75d5dba, 0x2b191932, 0x957373e6,
	0xa06060c0, 0x98818119, 0xd14f4f9e, 0x7fdcdca3, 0x66222244, 0x7e2a2a54,
	0xab90903b, 0x8388880b, 0xca46468c, 0x29eeeec7, 0xd3b8b86b, 0x3c141428,
	0x79dedea7, 0xe25e5ebc, 0x1d0b0b16, 0x76dbdbad, 0x3be0e0db, 0x56323264,
	0x4e3a3a74, 0x1e0a0a14, 0xdb494992, 0xa06060c, 0x6c242448, 0xe45c5cb8,
	0x5dc2c29f, 0x6ed3d3bd, 0xefacac43, 0xa66262c4, 0xa8919139, 0xa4959531,
	0x37e4e4d3, 0x8b7979f2, 0x32e7e7d5, 0x43c8c88b, 0x5937376e, 0xb76d6dda,
	0x8c8d8d01, 0x64d5d5b1, 0xd24e4e9c, 0xe0a9a949, 0xb46c6cd8, 0xfa5656ac,
	0x7f4f4f3, 0x25eaeacf, 0xaf6565ca, 0x8e7a7af4, 0xe9aeae47, 0x18080810,
	0xd5baba6f, 0x887878f0, 0x6f25254a, 0x722e2e5c, 0x241c1c38, 0xf1a6a657,
	0xc7b4b473, 0x51c6c697, 0x23e8e8cb, 0x7cdddda1, 0x9c7474e8, 0x211f1f3e,
	0xdd4b4b96, 0xdcbdbd61, 0x868b8b0d, 0x858a8a0f, 0x907070e0, 0x423e3e7c,
	0xc4b5b571, 0xaa6666cc, 0xd8484890, 0x5030306, 0x1f6f6f7, 0x120e0e1c,
	0xa36161c2, 0x5f35356a, 0xf95757ae, 0xd0b9b969, 0x91868617, 0x58c1c199,
	0x271d1d3a, 0xb99e9e27, 0x38e1e1d9, 0x13f8f8eb, 0xb398982b, 0x33111122,
	0xbb6969d2, 0x70d9d9a9, 0x898e8e07, 0xa7949433, 0xb69b9b2d, 0x221e1e3c,
	0x92878715, 0x20e9e9c9, 0x49cece87, 0xff5555aa, 0x78282850, 0x7adfdfa5,
	0x8f8c8c03, 0xf8a1a159, 0x80898909, 0x170d0d1a, 0xdabfbf65, 0x31e6e6d7,
	0xc6424284, 0xb86868d0, 0xc3414182, 0xb0999929, 0x772d2d5a, 0x110f0f1e,
	0xcbb0b07b, 0xfc5454a8, 0xd6bbbb6d, 0x3a16162c}

var aes_rtable = [...]uint32{
	0x50a7f451, 0x5365417e, 0xc3a4171a, 0x965e273a, 0xcb6bab3b, 0xf1459d1f,
	0xab58faac, 0x9303e34b, 0x55fa3020, 0xf66d76ad, 0x9176cc88, 0x254c02f5,
	0xfcd7e54f, 0xd7cb2ac5, 0x80443526, 0x8fa362b5, 0x495ab1de, 0x671bba25,
	0x980eea45, 0xe1c0fe5d, 0x2752fc3, 0x12f04c81, 0xa397468d, 0xc6f9d36b,
	0xe75f8f03, 0x959c9215, 0xeb7a6dbf, 0xda595295, 0x2d83bed4, 0xd3217458,
	0x2969e049, 0x44c8c98e, 0x6a89c275, 0x78798ef4, 0x6b3e5899, 0xdd71b927,
	0xb64fe1be, 0x17ad88f0, 0x66ac20c9, 0xb43ace7d, 0x184adf63, 0x82311ae5,
	0x60335197, 0x457f5362, 0xe07764b1, 0x84ae6bbb, 0x1ca081fe, 0x942b08f9,
	0x58684870, 0x19fd458f, 0x876cde94, 0xb7f87b52, 0x23d373ab, 0xe2024b72,
	0x578f1fe3, 0x2aab5566, 0x728ebb2, 0x3c2b52f, 0x9a7bc586, 0xa50837d3,
	0xf2872830, 0xb2a5bf23, 0xba6a0302, 0x5c8216ed, 0x2b1ccf8a, 0x92b479a7,
	0xf0f207f3, 0xa1e2694e, 0xcdf4da65, 0xd5be0506, 0x1f6234d1, 0x8afea6c4,
	0x9d532e34, 0xa055f3a2, 0x32e18a05, 0x75ebf6a4, 0x39ec830b, 0xaaef6040,
	0x69f715e, 0x51106ebd, 0xf98a213e, 0x3d06dd96, 0xae053edd, 0x46bde64d,
	0xb58d5491, 0x55dc471, 0x6fd40604, 0xff155060, 0x24fb9819, 0x97e9bdd6,
	0xcc434089, 0x779ed967, 0xbd42e8b0, 0x888b8907, 0x385b19e7, 0xdbeec879,
	0x470a7ca1, 0xe90f427c, 0xc91e84f8, 0x0, 0x83868009, 0x48ed2b32,
	0xac70111e, 0x4e725a6c, 0xfbff0efd, 0x5638850f, 0x1ed5ae3d, 0x27392d36,
	0x64d90f0a, 0x21a65c68, 0xd1545b9b, 0x3a2e3624, 0xb1670a0c, 0xfe75793,
	0xd296eeb4, 0x9e919b1b, 0x4fc5c080, 0xa220dc61, 0x694b775a, 0x161a121c,
	0xaba93e2, 0xe52aa0c0, 0x43e0223c, 0x1d171b12, 0xb0d090e, 0xadc78bf2,
	0xb9a8b62d, 0xc8a91e14, 0x8519f157, 0x4c0775af, 0xbbdd99ee, 0xfd607fa3,
	0x9f2601f7, 0xbcf5725c, 0xc53b6644, 0x347efb5b, 0x7629438b, 0xdcc623cb,
	0x68fcedb6, 0x63f1e4b8, 0xcadc31d7, 0x10856342, 0x40229713, 0x2011c684,
	0x7d244a85, 0xf83dbbd2, 0x1132f9ae, 0x6da129c7, 0x4b2f9e1d, 0xf330b2dc,
	0xec52860d, 0xd0e3c177, 0x6c16b32b, 0x99b970a9, 0xfa489411, 0x2264e947,
	0xc48cfca8, 0x1a3ff0a0, 0xd82c7d56, 0xef903322, 0xc74e4987, 0xc1d138d9,
	0xfea2ca8c, 0x360bd498, 0xcf81f5a6, 0x28de7aa5, 0x268eb7da, 0xa4bfad3f,
	0xe49d3a2c, 0xd927850, 0x9bcc5f6a, 0x62467e54, 0xc2138df6, 0xe8b8d890,
	0x5ef7392e, 0xf5afc382, 0xbe805d9f, 0x7c93d069, 0xa92dd56f, 0xb31225cf,
	0x3b99acc8, 0xa77d1810, 0x6e639ce8, 0x7bbb3bdb, 0x97826cd, 0xf418596e,
	0x1b79aec, 0xa89a4f83, 0x656e95e6, 0x7ee6ffaa, 0x8cfbc21, 0xe6e815ef,
	0xd99be7ba, 0xce366f4a, 0xd4099fea, 0xd67cb029, 0xafb2a431, 0x31233f2a,
	0x3094a5c6, 0xc066a235, 0x37bc4e74, 0xa6ca82fc, 0xb0d090e0, 0x15d8a733,
	0x4a9804f1, 0xf7daec41, 0xe50cd7f, 0x2ff69117, 0x8dd64d76, 0x4db0ef43,
	0x544daacc, 0xdf0496e4, 0xe3b5d19e, 0x1b886a4c, 0xb81f2cc1, 0x7f516546,
	0x4ea5e9d, 0x5d358c01, 0x737487fa, 0x2e410bfb, 0x5a1d67b3, 0x52d2db92,
	0x335610e9, 0x1347d66d, 0x8c61d79a, 0x7a0ca137, 0x8e14f859, 0x893c13eb,
	0xee27a9ce, 0x35c961b7, 0xede51ce1, 0x3cb1477a, 0x59dfd29c, 0x3f73f255,
	0x79ce1418, 0xbf37c773, 0xeacdf753, 0x5baafd5f, 0x146f3ddf, 0x86db4478,
	0x81f3afca, 0x3ec468b9, 0x2c342438, 0x5f40a3c2, 0x72c31d16, 0xc25e2bc,
	0x8b493c28, 0x41950dff, 0x7101a839, 0xdeb30c08, 0x9ce4b4d8, 0x90c15664,
	0x6184cb7b, 0x70b632d5, 0x745c6c48, 0x4257b8d0}

type AES struct {
	Nk   int
	Nr   int
	mode int
	fkey [60]uint32
	rkey [60]uint32
	f    [16]byte
}

/* Rotates 32-bit word left by 1, 2 or 3 byte  */

func aes_ROTL8(x uint32) uint32 {
	return (((x) << 8) | ((x) >> 24))
}

func aes_ROTL16(x uint32) uint32 {
	return (((x) << 16) | ((x) >> 16))
}

func aes_ROTL24(x uint32) uint32 {
	return (((x) << 24) | ((x) >> 8))
}

func aes_pack(b [4]byte) uint32 { /* pack bytes into a 32-bit Word */
	return ((uint32(b[3]) & 0xff) << 24) | ((uint32(b[2]) & 0xff) << 16) | ((uint32(b[1]) & 0xff) << 8) | (uint32(b[0]) & 0xff)
}

func aes_unpack(a uint32) [4]byte { /* unpack bytes from a word */
	var b = [4]byte{byte(a & 0xff), byte((a >> 8) & 0xff), byte((a >> 16) & 0xff), byte((a >> 24) & 0xff)}
	return b
}

func aes_bmul(x byte, y byte) byte { /* x.y= AntiLog(Log(x) + Log(y)) */

	ix := int(x) & 0xff
	iy := int(y) & 0xff
	lx := int(aes_ltab[ix]) & 0xff
	ly := int(aes_ltab[iy]) & 0xff

	if x != 0 && y != 0 {
		return aes_ptab[(lx+ly)%255]
	} else {
		return byte(0)
	}
}

func aes_SubByte(a uint32) uint32 {
	b := aes_unpack(a)
	b[0] = aes_fbsub[int(b[0])]
	b[1] = aes_fbsub[int(b[1])]
	b[2] = aes_fbsub[int(b[2])]
	b[3] = aes_fbsub[int(b[3])]
	return aes_pack(b)
}

func aes_product(x uint32, y uint32) byte { /* dot product of two 4-byte arrays */
	xb := aes_unpack(x)
	yb := aes_unpack(y)

	return (aes_bmul(xb[0], yb[0]) ^ aes_bmul(xb[1], yb[1]) ^ aes_bmul(xb[2], yb[2]) ^ aes_bmul(xb[3], yb[3]))
}

func aes_InvMixCol(x uint32) uint32 { /* matrix Multiplication */
	var b [4]byte
	m := aes_pack(aes_InCo)
	b[3] = aes_product(m, x)
	m = aes_ROTL24(m)
	b[2] = aes_product(m, x)
	m = aes_ROTL24(m)
	b[1] = aes_product(m, x)
	m = aes_ROTL24(m)
	b[0] = aes_product(m, x)
	var y = aes_pack(b)
	return y
}

func aes_increment(f []byte) {
	for i := 0; i < 16; i++ {
		f[i]++
		if f[i] != 0 {
			break
		}
	}
}

/* reset cipher */
func (A *AES) Reset(m int, iv []byte) { /* reset mode, or reset iv */
	A.mode = m
	for i := 0; i < 16; i++ {
		A.f[i] = 0
	}
	if (A.mode != AES_ECB) && (iv != nil) {
		for i := 0; i < 16; i++ {
			A.f[i] = iv[i]
		}
	}
}

func (A *AES) Init(m int, nk int, key []byte, iv []byte) bool {
	/* Key Scheduler. Create expanded encryption key */
	var CipherKey [8]uint32
	var b [4]byte
	nk /= 4
	if nk != 4 && nk != 6 && nk != 8 {
		return false
	}
	nr := 6 + nk
	A.Nk = nk
	A.Nr = nr
	A.Reset(m, iv)
	N := 4 * (nr + 1)

	j := 0
	for i := 0; i < nk; i++ {
		for k := 0; k < 4; k++ {
			b[k] = key[j+k]
		}
		CipherKey[i] = aes_pack(b)
		j += 4
	}
	for i := 0; i < nk; i++ {
		A.fkey[i] = CipherKey[i]
	}

	j = nk
	for k := 0; j < N; k++ {
		A.fkey[j] = A.fkey[j-nk] ^ aes_SubByte(aes_ROTL24(A.fkey[j-1])) ^ uint32(aes_rco[k])
		if nk <= 6 {
			for i := 1; i < nk && (i+j) < N; i++ {
				A.fkey[i+j] = A.fkey[i+j-nk] ^ A.fkey[i+j-1]
			}
		} else {
			i := 0
			for i = 1; i < 4 && (i+j) < N; i++ {
				A.fkey[i+j] = A.fkey[i+j-nk] ^ A.fkey[i+j-1]
			}
			if (j + 4) < N {
				A.fkey[j+4] = A.fkey[j+4-nk] ^ aes_SubByte(A.fkey[j+3])
			}
			for i = 5; i < nk && (i+j) < N; i++ {
				A.fkey[i+j] = A.fkey[i+j-nk] ^ A.fkey[i+j-1]
			}
		}
		j += nk

	}

	/* now for the expanded decrypt key in reverse order */

	for j := 0; j < 4; j++ {
		A.rkey[j+N-4] = A.fkey[j]
	}
	for i := 4; i < N-4; i += 4 {
		k := N - 4 - i
		for j := 0; j < 4; j++ {
			A.rkey[k+j] = aes_InvMixCol(A.fkey[i+j])
		}
	}
	for j := N - 4; j < N; j++ {
		A.rkey[j-N+4] = A.fkey[j]
	}
	return true
}

func NewAES() *AES {
	var A = new(AES)
	return A
}

func (A *AES) Getreg() [16]byte {
	var ir [16]byte
	for i := 0; i < 16; i++ {
		ir[i] = A.f[i]
	}
	return ir
}

/* Encrypt a single block */
func (A *AES) ecb_encrypt(buff []byte) {
	var b [4]byte
	var p [4]uint32
	var q [4]uint32

	j := 0
	for i := 0; i < 4; i++ {
		for k := 0; k < 4; k++ {
			b[k] = buff[j+k]
		}
		p[i] = aes_pack(b)
		p[i] ^= A.fkey[i]
		j += 4
	}

	k := 4

	/* State alternates between p and q */
	for i := 1; i < A.Nr; i++ {
		q[0] = A.fkey[k] ^ aes_ftable[int(p[0]&0xff)] ^ aes_ROTL8(aes_ftable[int((p[1]>>8)&0xff)]) ^ aes_ROTL16(aes_ftable[int((p[2]>>16)&0xff)]) ^ aes_ROTL24(aes_ftable[int((p[3]>>24)&0xff)])

		q[1] = A.fkey[k+1] ^ aes_ftable[int(p[1]&0xff)] ^ aes_ROTL8(aes_ftable[int((p[2]>>8)&0xff)]) ^ aes_ROTL16(aes_ftable[int((p[3]>>16)&0xff)]) ^ aes_ROTL24(aes_ftable[int((p[0]>>24)&0xff)])

		q[2] = A.fkey[k+2] ^ aes_ftable[int(p[2]&0xff)] ^ aes_ROTL8(aes_ftable[int((p[3]>>8)&0xff)]) ^ aes_ROTL16(aes_ftable[int((p[0]>>16)&0xff)]) ^ aes_ROTL24(aes_ftable[int((p[1]>>24)&0xff)])

		q[3] = A.fkey[k+3] ^ aes_ftable[int(p[3]&0xff)] ^ aes_ROTL8(aes_ftable[int((p[0]>>8)&0xff)]) ^ aes_ROTL16(aes_ftable[int((p[1]>>16)&0xff)]) ^ aes_ROTL24(aes_ftable[int((p[2]>>24)&0xff)])

		k += 4
		for j = 0; j < 4; j++ {
			t := p[j]
			p[j] = q[j]
			q[j] = t
		}
	}

	/* Last Round */

	q[0] = A.fkey[k] ^ uint32(aes_fbsub[int(p[0]&0xff)]) ^ aes_ROTL8(uint32(aes_fbsub[int((p[1]>>8)&0xff)])) ^ aes_ROTL16(uint32(aes_fbsub[int((p[2]>>16)&0xff)])) ^ aes_ROTL24(uint32(aes_fbsub[int((p[3]>>24)&0xff)]))

	q[1] = A.fkey[k+1] ^ uint32(aes_fbsub[int(p[1]&0xff)]) ^ aes_ROTL8(uint32(aes_fbsub[int((p[2]>>8)&0xff)])) ^ aes_ROTL16(uint32(aes_fbsub[int((p[3]>>16)&0xff)])) ^ aes_ROTL24(uint32(aes_fbsub[int((p[0]>>24)&0xff)]))

	q[2] = A.fkey[k+2] ^ uint32(aes_fbsub[int(p[2]&0xff)]) ^ aes_ROTL8(uint32(aes_fbsub[int((p[3]>>8)&0xff)])) ^ aes_ROTL16(uint32(aes_fbsub[int((p[0]>>16)&0xff)])) ^ aes_ROTL24(uint32(aes_fbsub[int((p[1]>>24)&0xff)]))

	q[3] = A.fkey[k+3] ^ uint32(aes_fbsub[int(p[3]&0xff)]) ^ aes_ROTL8(uint32(aes_fbsub[int((p[0]>>8)&0xff)])) ^ aes_ROTL16(uint32(aes_fbsub[int((p[1]>>16)&0xff)])) ^ aes_ROTL24(uint32(aes_fbsub[int((p[2]>>24)&0xff)]))

	j = 0
	for i := 0; i < 4; i++ {
		b = aes_unpack(q[i])
		for k = 0; k < 4; k++ {
			buff[j+k] = b[k]
		}
		j += 4
	}
}

/* Decrypt a single block */
func (A *AES) ecb_decrypt(buff []byte) {
	var b [4]byte
	var p [4]uint32
	var q [4]uint32

	j := 0
	for i := 0; i < 4; i++ {
		for k := 0; k < 4; k++ {
			b[k] = buff[j+k]
		}
		p[i] = aes_pack(b)
		p[i] ^= A.rkey[i]
		j += 4
	}

	k := 4

	/* State alternates between p and q */
	for i := 1; i < A.Nr; i++ {

		q[0] = A.rkey[k] ^ aes_rtable[int(p[0]&0xff)] ^ aes_ROTL8(aes_rtable[int((p[3]>>8)&0xff)]) ^ aes_ROTL16(aes_rtable[int((p[2]>>16)&0xff)]) ^ aes_ROTL24(aes_rtable[int((p[1]>>24)&0xff)])

		q[1] = A.rkey[k+1] ^ aes_rtable[int(p[1]&0xff)] ^ aes_ROTL8(aes_rtable[int((p[0]>>8)&0xff)]) ^ aes_ROTL16(aes_rtable[int((p[3]>>16)&0xff)]) ^ aes_ROTL24(aes_rtable[int((p[2]>>24)&0xff)])

		q[2] = A.rkey[k+2] ^ aes_rtable[int(p[2]&0xff)] ^ aes_ROTL8(aes_rtable[int((p[1]>>8)&0xff)]) ^ aes_ROTL16(aes_rtable[int((p[0]>>16)&0xff)]) ^ aes_ROTL24(aes_rtable[int((p[3]>>24)&0xff)])

		q[3] = A.rkey[k+3] ^ aes_rtable[int(p[3]&0xff)] ^ aes_ROTL8(aes_rtable[int((p[2]>>8)&0xff)]) ^ aes_ROTL16(aes_rtable[int((p[1]>>16)&0xff)]) ^ aes_ROTL24(aes_rtable[int((p[0]>>24)&0xff)])

		k += 4
		for j := 0; j < 4; j++ {
			t := p[j]
			p[j] = q[j]
			q[j] = t
		}
	}

	/* Last Round */

	q[0] = A.rkey[k] ^ uint32(aes_rbsub[int(p[0]&0xff)]) ^ aes_ROTL8(uint32(aes_rbsub[int((p[3]>>8)&0xff)])) ^ aes_ROTL16(uint32(aes_rbsub[int((p[2]>>16)&0xff)])) ^ aes_ROTL24(uint32(aes_rbsub[int((p[1]>>24)&0xff)]))

	q[1] = A.rkey[k+1] ^ uint32(aes_rbsub[int(p[1]&0xff)]) ^ aes_ROTL8(uint32(aes_rbsub[int((p[0]>>8)&0xff)])) ^ aes_ROTL16(uint32(aes_rbsub[int((p[3]>>16)&0xff)])) ^ aes_ROTL24(uint32(aes_rbsub[int((p[2]>>24)&0xff)]))

	q[2] = A.rkey[k+2] ^ uint32(aes_rbsub[int(p[2]&0xff)]) ^ aes_ROTL8(uint32(aes_rbsub[int((p[1]>>8)&0xff)])) ^ aes_ROTL16(uint32(aes_rbsub[int((p[0]>>16)&0xff)])) ^ aes_ROTL24(uint32(aes_rbsub[int((p[3]>>24)&0xff)]))

	q[3] = A.rkey[k+3] ^ uint32(aes_rbsub[int((p[3])&0xff)]) ^ aes_ROTL8(uint32(aes_rbsub[int((p[2]>>8)&0xff)])) ^ aes_ROTL16(uint32(aes_rbsub[int((p[1]>>16)&0xff)])) ^ aes_ROTL24(uint32(aes_rbsub[int((p[0]>>24)&0xff)]))

	j = 0
	for i := 0; i < 4; i++ {
		b = aes_unpack(q[i])
		for k := 0; k < 4; k++ {
			buff[j+k] = b[k]
		}
		j += 4
	}
}

/* Encrypt using selected mode of operation */
func (A *AES) Encrypt(buff []byte) uint32 {
	var st [16]byte

	// Supported Modes of Operation

	var fell_off uint32 = 0
	switch A.mode {
	case AES_ECB:
		A.ecb_encrypt(buff)
		return 0
	case AES_CBC:
		for j := 0; j < 16; j++ {
			buff[j] ^= A.f[j]
		}
		A.ecb_encrypt(buff)
		for j := 0; j < 16; j++ {
			A.f[j] = buff[j]
		}
		return 0

	case AES_CFB1:
		fallthrough
	case AES_CFB2:
		fallthrough
	case AES_CFB4:
		bytes := A.mode - AES_CFB1 + 1
		for j := 0; j < bytes; j++ {
			fell_off = (fell_off << 8) | uint32(A.f[j])
		}
		for j := 0; j < 16; j++ {
			st[j] = A.f[j]
		}
		for j := bytes; j < 16; j++ {
			A.f[j-bytes] = A.f[j]
		}
		A.ecb_encrypt(st[:])
		for j := 0; j < bytes; j++ {
			buff[j] ^= st[j]
			A.f[16-bytes+j] = buff[j]
		}
		return fell_off

	case AES_OFB1:
		fallthrough
	case AES_OFB2:
		fallthrough
	case AES_OFB4:
		fallthrough
	case AES_OFB8:
		fallthrough
	case AES_OFB16:

		bytes := A.mode - AES_OFB1 + 1
		A.ecb_encrypt(A.f[:])
		for j := 0; j < bytes; j++ {
			buff[j] ^= A.f[j]
		}
		return 0

	case AES_CTR1:
		fallthrough
	case AES_CTR2:
		fallthrough
	case AES_CTR4:
		fallthrough
	case AES_CTR8:
		fallthrough
	case AES_CTR16:
		bytes := A.mode - AES_CTR1 + 1
		for j := 0; j < 16; j++ {
			st[j] = A.f[j]
		}
		A.ecb_encrypt(st[:])
		for j := 0; j < bytes; j++ {
			buff[j] ^= st[j]
		}
		aes_increment(A.f[:])
		return 0

	default:
		return 0
	}
}

/* Decrypt using selected mode of operation */
func (A *AES) Decrypt(buff []byte) uint32 {

	var st [16]byte

	// Supported Modes of Operation

	var fell_off uint32 = 0
	switch A.mode {
	case AES_ECB:
		A.ecb_decrypt(buff)
		return 0
	case AES_CBC:
		for j := 0; j < 16; j++ {
			st[j] = A.f[j]
			A.f[j] = buff[j]
		}
		A.ecb_decrypt(buff)
		for j := 0; j < 16; j++ {
			buff[j] ^= st[j]
			st[j] = 0
		}
		return 0
	case AES_CFB1:
		fallthrough
	case AES_CFB2:
		fallthrough
	case AES_CFB4:
		bytes := A.mode - AES_CFB1 + 1
		for j := 0; j < bytes; j++ {
			fell_off = (fell_off << 8) | uint32(A.f[j])
		}
		for j := 0; j < 16; j++ {
			st[j] = A.f[j]
		}
		for j := bytes; j < 16; j++ {
			A.f[j-bytes] = A.f[j]
		}
		A.ecb_encrypt(st[:])
		for j := 0; j < bytes; j++ {
			A.f[16-bytes+j] = buff[j]
			buff[j] ^= st[j]
		}
		return fell_off
	case AES_OFB1:
		fallthrough
	case AES_OFB2:
		fallthrough
	case AES_OFB4:
		fallthrough
	case AES_OFB8:
		fallthrough
	case AES_OFB16:
		bytes := A.mode - AES_OFB1 + 1
		A.ecb_encrypt(A.f[:])
		for j := 0; j < bytes; j++ {
			buff[j] ^= A.f[j]
		}
		return 0

	case AES_CTR1:
		fallthrough
	case AES_CTR2:
		fallthrough
	case AES_CTR4:
		fallthrough
	case AES_CTR8:
		fallthrough
	case AES_CTR16:
		bytes := A.mode - AES_CTR1 + 1
		for j := 0; j < 16; j++ {
			st[j] = A.f[j]
		}
		A.ecb_encrypt(st[:])
		for j := 0; j < bytes; j++ {
			buff[j] ^= st[j]
		}
		aes_increment(A.f[:])
		return 0

	default:
		return 0
	}
}

/* Clean up and delete left-overs */
func (A *AES) End() { // clean up
	for i := 0; i < 4*(A.Nr+1); i++ {
		A.fkey[i] = 0
		A.rkey[i] = 0
	}
	for i := 0; i < 16; i++ {
		A.f[i] = 0
	}
}

/* AES encryption/decryption. Encrypt byte array M using key K and returns ciphertext */
func AES_CBC_IV0_ENCRYPT(K []byte, M []byte) []byte { /* AES CBC encryption, with Null IV and key K */
	/* Input is from an octet string M, output is to an octet string C */
	/* Input is padded as necessary to make up a full final block */
	a := NewAES()
	fin := false

	var buff [16]byte
	var C []byte

	a.Init(AES_CBC, len(K), K, nil)

	ipt := 0 //opt:=0
	var i int
	for true {
		for i = 0; i < 16; i++ {
			if ipt < len(M) {
				buff[i] = M[ipt]
				ipt++
			} else {
				fin = true
				break
			}
		}
		if fin {
			break
		}
		a.Encrypt(buff[:])
		for i = 0; i < 16; i++ {
			C = append(C, buff[i])
		}
	}

	/* last block, filled up to i-th index */

	padlen := 16 - i
	for j := i; j < 16; j++ {
		buff[j] = byte(padlen)
	}

	a.Encrypt(buff[:])

	for i = 0; i < 16; i++ {
		C = append(C, buff[i])
	}
	a.End()
	return C
}

/* returns plaintext if all consistent, else returns null string */
func AES_CBC_IV0_DECRYPT(K []byte, C []byte) []byte { /* padding is removed */
	a := NewAES()
	var buff [16]byte
	var MM []byte
	var M []byte

	var i int
	ipt := 0
	opt := 0

	a.Init(AES_CBC, len(K), K, nil)

	if len(C) == 0 {
		return nil
	}
	ch := C[ipt]
	ipt++

	fin := false

	for true {
		for i = 0; i < 16; i++ {
			buff[i] = ch
			if ipt >= len(C) {
				fin = true
				break
			} else {
				ch = C[ipt]
				ipt++
			}
		}
		a.Decrypt(buff[:])
		if fin {
			break
		}
		for i = 0; i < 16; i++ {
			MM = append(MM, buff[i])
			opt++
		}
	}

	a.End()
	bad := false
	padlen := int(buff[15])
	if i != 15 || padlen < 1 || padlen > 16 {
		bad = true
	}
	if padlen >= 2 && padlen <= 16 {
		for i = 16 - padlen; i < 16; i++ {
			if buff[i] != byte(padlen) {
				bad = true
			}
		}
	}

	if !bad {
		for i = 0; i < 16-padlen; i++ {
			MM = append(MM, buff[i])
			opt++
		}
	}

	if bad {
		return nil
	}

	for i = 0; i < opt; i++ {
		M = append(M, MM[i])
	}

	return M
}

/*
func main() {
	var key [32]byte
	var block [16]byte
	var iv [16]byte

	for i:=0;i<32;i++ {key[i]=0}
	key[0]=1
	for i:=0;i<16;i++ {iv[i]=byte(i)}
	for i:=0;i<16;i++ {block[i]=byte(i)}

	a:=NewAES()

	a.Init(AES_CTR16,32,key[:],iv[:])
	fmt.Printf("Plain= \n")
	for i:=0;i<16;i++  {fmt.Printf("%02X ", block[i]&0xff)}
	fmt.Printf("\n")

	a.Encrypt(block[:])

	fmt.Printf("Encrypt= \n")
	for i:=0;i<16;i++  {fmt.Printf("%02X ", block[i]&0xff)}
	fmt.Printf("\n")

	a.Reset(AES_CTR16,iv[:])
	a.Decrypt(block[:])

	fmt.Printf("Decrypt= \n")
	for i:=0;i<16;i++  {fmt.Printf("%02X ", block[i]&0xff)}
	fmt.Printf("\n")

	a.End();
}
*/
